How do you create the ultimate horror movie mask? That was the problem facing Doctor Strange and Sinister filmmaker Scott Derrickson as he was prepping his new movie, the Blumhouse-produced The Black Phone (out today). In the '70s-set movie, Ethan Hawke plays "the Grabber," a character who kidnaps and kills children, and through most of the film same wears a dementedly grinning mask, or variations on the same. Derrickson was aware that getting the mask right was crucial for the film's success, both artistically and commercially.